*{
    margin: 0;
    padding: 0;
}
a{
    text-decoration: none;
}
ul li{
    list-style: none;
}
.f1{
    float: left;
}
.f2{
    float: right;
}
.banxin{
    width: ;
    margin-left: auto;
    margin-right: auto;
}
.clearfix{
    zoom: 1;
}
.clearfix:after{
    display: table;
    content: " ";
    clear: both;   
}